Prince's unreleased music could make estate more valuable than Michael Jackson's

A bounty of thousands of never-before-heard Prince songs could extend the late singer's earning potential and star power for decades — a catalog one expert said could be more valuable than that of Michael Jackson.

The 2015 documentary "Hunting For Prince's Vault," directed by journalist Mobeen Azhar, centers on the quest to uncover what former Prince sound engineers said was up to 2,000 unreleased songs, a stockpile that would fetch any eventual Prince beneficiary untold financial returns.

The quantity is staggering, but not surprising given the notoriously fickle artist, who would gather producers and musicians in the middle of the night to record entire albums over several hours — only to delete them out of boredom or creative qualms.

"I think over 70 percent of the music we've worked on for Prince is yet to be released. There are a lot of songs that were sent to us clearly with the idea that they would never be released," composer and Prince collaborator Brent Fischer told Azhar in 2015 for the BBC.

"We would just write, write, write and then put things to the side and fix them later. Some of his best stuff is in the vault," said Cat Glover, who was billed as a Prince protege and muse in a 2015 interview with U.K. publication The Guardian.

Aside from the artistic implications — the timeless pop-funk sound attributed to Prince could keep the singer, who died at 57 on Thursday, a contemporary artist for well into the next century — there is major potential for financial gain for the lucky inheritor of his estate.

"All of our clients have these really valuable rights the same as Prince, and when they're gone they explode," said Laura Zwicker, head of law firm Greenberg Glusker's Private Client Services Group.

"We can look to the Michael Jackson estate tax litigation right now to get a sense of what it could be calculable at — my guess is it's actually more valuable than the Jackson estate," Zwicker said.

The tax litigation Zwicker mentioned is a years-long squabble between Jackson attorneys and the IRS, which wants 40 percent in taxes on an estate the agency values at $434 million when accounting for his body of work, name, image and likeness. The Jackson estate has a dramatically different valuation — $2,105 (and, yes, you read that correctly).

"Prince had significantly less baggage than Michael Jackson," Zwicker said. "Projections at this moment would be liquid and speculative, and it's hard to say how long Prince will stay in vogue, but [there's] a lot of value."

TheWrap previously reported on who might control that valuable Prince estate — one that will emerge with ownership of Prince's full song catalog and free reign to license all music recorded outside of the artist's long relationship with Warner Bros. Records.

It's a heavy crown, according to Zwicker, one assisted by artists who have the foresight to leave estate planning documents which she said does not happen as routinely as it should.

"If he actually planned, he could have both estate planning documents that would make it so clear who controls the catalog, his name and likeness, and who has the right to monetize that. It's the voice that decides if he becomes a [touring] hologram, or appears in a Pepsi commercial."

Potential Prince beneficiaries are currently unknown. He has no living children. The singer was married twice, to Mayte Garcia from 1996 to 1999 and to Manuela Testolini from 2001 to 2006. Garcia and Prince did welcome a son, Boy Gregory, who died as the result of Pfeiffer syndrome a week after his birth.